1. Field of the Invention
The present invention relates to a vehicle bumper structure that detects a collision with an object such as a pedestrian or the like.
2. Background of the Invention
Japanese Patent Application Publication No. 2000-225907 (JP-A-2000-225907) describes an arrangement in which a load sensor that detects a frontal collision of a vehicle with an object, e.g., a pedestrian is provided. Specifically, a groove extending in the vehicle width direction is formed in a front surface of the front-bumper reinforcement, and an elongated load sensor is placed in the groove, flush with the front surface. On the back surface of the front-bumper absorber, a pair of upper and lower grooves extending in the vehicle width direction are formed. A protruding portion (or a push portion) provided between the upper and the lower groove is disposed to correspond to the load sensor.
However, the vehicle bumper structure described in JP-A-2000-225907 leaves a room for improvement in the following aspects. Specifically, if the thickness of the front-bumper absorber (when viewed from above) differs from part to part or if the rigidity of the front-bumper reinforcement differs in the vehicle width direction, the characteristics of the load transferred to the front-bumper reinforcement through the front-bumper absorber will be different at the time of front collision with an object. In this case, the sensitivity (output) of the load sensor provided between the front-bumper absorber and the front-bumper reinforcement to sense the load imparted thereto in the vehicle longitudinal direction will vary depending on the region of impact, which makes it difficult to accurately sense a collision.